The present invention relates to an electrical connector clip for medical sensors, to a medical device comprising said clip and to a method for detecting blood leakage in extracorporeal blood treatments using said medical device.
In particular, the present invention relates to an electrical connector clip suitable for a sensor of an extravasation detection device and to an extravasation detection device comprising said connector.
During extra corporal blood treatments, such as dialysis and/or filtration treatment, accidental needle-fistula disconnection or blood leakage must be avoided. To this aim, a patch is attached to the body of the patient on or near the needle-fistula. The patch is a sheet sensor comprising two electrodes covered by an hydrophilic layer which may be located near the needle or below the arm. The electrodes are connected by means of cable to an alarm unit. In case of blood leakage, once sufficient blood is present inside the hydrophilic layer between the electrodes, the electrical properties of the sensor change and the alarm unit generates an alarm alerting the user. The electrical connection between the sensor and the cable is provided by a connector which allows the user to change the sheet sensor after each treatment.
Sheet sensor and connector of the type described above are known for example from document WO9926686. This document discloses a medical extravasation detection device comprising a sensor that can attach to the skin for sensing electrical information. Tissue impedance is calculated from the sensor signals. The patch has elongate pick-up electrodes inboard of elongate energizing electrodes. The presence of an extravasation is determined by interpreting the tissue impedance measurement. Sensor is provided with a coupling region shaped and dimensioned to fit within a clip. Clip is provided with electrical contacts positioned within the clip so that they can contact surface electrodes when conductor-patch is placed within clip. Clip has electrical leads which connect to a constant alternating current source of power and electrical leads which connects to voltage potential measuring circuitry. Clip further includes a first conduit housing leads which connects to a device which interprets the data sensed by sensor and a second conduit which connects to a CT injector. Conduit has capability to halt operation of injector in the event an extravasation has been detected or to convey this information to injector.
The applicant has found that known electrical connector clips can be improved in many aspects from the functional and structural points of view.
In particular, the applicant has found that the connectors of the known type do not play an operational role in detecting the above mentioned sensor electrical properties change due to blood leakage, since the signal coming from the sensor is entirely managed by the alarm unit.
In particular, the applicant has found that the connectors of the known type do not allow the alarm unit to verify that the above mentioned sensor is correctly inserted inside the connector and that the build up electrical circuit will allows to monitor the change due to blood leakage at the sensor level by the alarm unit.
Furthermore, the applicant has found that the connectors of the known type cannot assure the mechanical lock onto the sensor and cannot confirm the electrical connection of the sensor to the alarm unit.
It is also known from document U.S. Pat. No. 6,152,754 a circuit board based cable connector for use with a sensor connector tab to establish electrical signal connection between a sensor and a monitor or processor. The connector comprises a housing which encloses a circuit board. A slot is formed through a leading edge of the housing to allow insertion of the connector tab. A release mechanism releasable secures the connector tab within the housing. The circuit board is positioned adjacent and generally parallel to the inserted connector tab. Traces are formed on the side of the circuit board opposite the connector tab and establish electrical connection between wires of a cable and connector arms of the circuit board. The connector arms extend generally parallel to the circuit board and are bent at their free ends to form dips. Slots formed through the circuit board are adapted to receive the dipped contact arm ends. The contact arm dips extend through the slots and into contact with electrical contacts of the connector tab, establishing an electrical connection. Two of the contact arms are adapted to connect to the same sensor tab contact so that the arms electrically communicate with each other when the tab is inserted into the connector. The contact arms are in electrical communication only when the sensor tab is correctly inserted into the connector. Thus, the contact arms can be adapted to communicate a signal when the connector tab is correctly connected and can also be adapted to trigger an alarm to indicate an improper connection or to indicate that the connector tab has fallen out of the connector. This connector above described is structurally complex and expensive.